Integrated Zinc oxide-on-silicon tactile-sensor array

Abstract

A 64-element piezoelectric tactile-sensor array, integrated on a silicon chip, has been fabricated and tested. The sensor array consists of 1µm-thick sputtered ZnO piezoelectric capacitors in an 8 × 8 matrix with each sensing element measuring 70 × 70µm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and spaced with a pitch of 70µm. Each sensor element is connected to an on-chip NMOS buffer-amplifier. The measured piezoelectric coefficient d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</inf> in the ZnO films is 14.4 pCN <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The measured voltage responsivity (at T=300K) is 5.2 mV/gm with a hysteresis-free linear response for loading to 200 gm.